Hydraulic table reciprocating mechanism



Nov. 24, 1942. D, H, HOLMES 2,302,909

HYDRAULIC TABLE RECIPROCATING MECHANISM Filed June 17, 1942 4 DUNA I7 H. HDLMEE Patented Nov. 24, 1942 HYDRAULIC TABLE RECIPROCATING MECHANISM Donald H. Holmes, Worcester, Mass., assignor to Norton Company, Worcester, Mass, a corporation of'Massachusetts Application June 1'7, 1342, Serial No. 441,461

Claims. (Cl. 121- --45) The invention relates to grinding machines, and more particularly to a hydraulically operated table reciprocating mechanism for a. grinding machine.

One object of the invention is to provide a simple and thoroughly practical table reciprocating invention is to provide a hydraulically operated table reciprocating mechanism in which a table actuated reversing valve is shifted by movement of the table to stop the flow of fluid in one direction and in which the valve is shifted into a reverse position by fluid under pressure. Another object of the invention'is to provide a table reversing mechanism including a table and reversing mechanism. Another object of the actuated reversing valve which is shifted into a 1 reverse position by fluid under pressure, and in which a control valve actuated by and in timed relation with the reversing valve serves to facilitate positive reversal ofthe va1ve. Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts, as will be exemplifled in the structure to be hereinafter described,

and the scope of the application of which will be'indicated in the following claims.

In the accompanying drawing in which is shown one of various possible embodiments of the mechanical features of this invention,

Fig. l is a hydraulic diagram of the improved table traversing mechanism;

Fig.2 is a fragmentary'vertical sectional View, on an enlarged scale, through the reversing lever and associated parts;

Fig. 3 is a fragmentary vertical sectional view, on an enlarged scale, taken approximately on the line 3--3 of Fig. 1;

Fig. 4 is a fragmentary sectional view, taken approximately on the line 44 of Fig. 3, showing the clamping and adjusting mechanism for the valve;

Fig. 5 is a vertical sectional view, taken approximately on the line 5-5 of Fig. 3; and

Fig. 6 is a similar vertical sectional view but with the valve parts shifted to the reverse position. 4

As illustrated in the drawing, the machine embodying this invention comprises a base I0 which supports a longitudinally reciprocable work supporting table H on the usual V-way and flat way (not shown) for a longitudinal reclprocatory movement relative to the base 6.

A fluid operated reciprocating mechanism is provided to reciprocate the'table comprising a fluid pressure cylinder |2 which is fixedly supported by bracket end caps- I3 and I4 fixedly mounted on the under side of the table II. The cylinder |2 contains a pair of spaced pistons l5 and I6 which are connected by a pair of hollow piston rods l1 and I8, respectively, with a pair of hollow brackets I9 and 26, respectively, mounted on opposite ends of the base Ill. The base [0 is preferably formed asa box-like structure containing in its lower portion a reservoir 2| for the fluid pressure system. Fluid is drawn from the reservoir 2| through a pipe 22 by means of a motor driven fluid pressure pump 23. The pump 23 forces fluid under pressure through a pipe 24 to'a table'control valve 25 A variable pressure relief valve 26 is connected in the pipe line 24 for passing excess fluid under pressure directly.

through a pipe 21 into the reservoir 2| so as to facilitate maintaining a uniform operating pressure within the hydraulic system.

The control valve 25 is preferably a piston type reversing valve which includes a movable a valve stem 28 having formed integrally therewith a plurality of valve pistons 29, 3| 3|, 32 and 33. Fluid under pressure from-the pump 23 is forced through the pipe 24 into a chamber 34 formed in the valve casing 25. In the position of the valve (Fig. 1), fluid under pressure within the chamber 34 passes through a port 35 into a valve chamber 36 located between the valve pistons 30 and 3| and .passes outwardly through a port.3l, through a passage 38, through a pipe 39, through a hollow chamber 4|] within the bracket l9, and through the hollow piston rod into a cylinder chamber 4| to move the cylinder 2 and table II toward the left (Fig. 1). Duringthe movement of the cylinder |2 and table I toward the left, fluid within a cylinder chamber 42 is exhausted through the hollow piston rod l8, through a hollow chamber 43 in the bracket 20, through a pipe 44, through a passage 45, through a port 46, into a cylinder chamber "located between the valve pistons 3| and 32. Fluid exhausting into the valve chamber 41 passes outwardly through a port 48, through a passage 49, and a pipe to a combined stop and start-and speed control valve 5|. Fluid exhausting through the pipe 50 passes through a V-shaped port 52in the valve 5|, into a valve chamber 53, and exhausts therefrom through a pipe 54, into the reservoir 2|.

The speed control valve 5| is preferably formed as an integral part of the valve 25 but for the sake of simplicity of illustration has been illustrated diagrammatically in Fig. 1 as a separate valve I.

valve unit. The valve 5| is preferably located in the exhaust side of the system so as to maintain a uniform fluid pressure on the operative side of the main cylinder during the entire reciprocatory stroke of the cylinder relative to the pistons. The valve 5| comprises a valve stem 55 having formed integrally therewith valve pistons 58 and 51. The throttle or control valve 5| is arranged so that it may be moved longitudinally from the full line to the dotted line position. The valve stem 55 is provided with an actuating knob 58 to facilitate a rotary adjustment of the valve. The right-hand end of the valve piston 51 is formed as an angular plane surface. By a rotary adjustment of the valve stem 55, the angular end surface of the valve piston 51 may open or close the V-port 52 to the desired and predetermined extent and serves as a fine adjustment to cut off more or less of the exhaust of fluid from the system, thereby precisely to regulate the reciprocatory speed of the table I I.

In order that the valve piston 51 may be maintained in the desired adjusted position, a serrated portion 59 is formed integral with the valve stem 55. A spring-pressed arrow-pointed plunger 58 is supported by the casing of the valve 5| and is maintained in engagement with the serrated por- -tion so that he valve stem 55 may be moved endwise or axially to stop or start the table movement without changing the speed adjustment thereof.

A manually operable start and stop lever 85 is pivotally supported by a stud 88 which is in turn supported by a projecting boss 61 formed integral .with an apron 58 which is fixedly supported. on

the front of the machine base I8. The lever 55 is provided with a clearance aperture 88 which surounds a sleeve I8. The sleeve I8 is connected by a pair of diametrically opposed studs 1| with the control lever 85. It will be readily apparent from the foregoing disclosure that when the control lever 85 is in the position indicated in full lines (Fig. 1), the V-port 52 will be uncovered, allowing the table to move at a desired speed governed by the rotary adjustment of the valve stem 55.

When itis desired to stop the reciprocatory movement of the table II, the control lever 85 is shifted in a clockwise direction into broken line position 850., which movement shifts the valve stem 55 together with the valve pistons 56 and 51 toward the right (Fig. 1) into the broken line position so-that the valve piston 57 closes the V-port 52, thus cutting off the exhaustof fluid from the table cylinder I2 to stop the reciprocatory movement of the table II.

When the throttle valve is in a closed position, it is desirable to provide a suitable by-pass whereby fluid may readily pass from the cylinder chamber 4| into th cylinder chamber 42 and vice versa to facilitate a manual traversing movement of the table I I. A pipe 88 is connected between the passage 38 in the valve 25 and the valve 5I. Similarly, a pipe 8| is connected between the pasage 45 in the valve 25 and with the When the valv stem 55 is moved toward the left (Fig. 1) into a table stop position,

. a valve chamber 82 located between the valve pistons 58 and 51 moves into position 82a so that fluid may readily pass between the pipes 88 and II to facilitate a free passage of fluid between the opposite end chambers of the table cylinder I2, so that the table II may be readily moved longitudinally without the necessity of overcoming fluid within the pressure system.

A manually operable table traverse mechanism may be utilized such as, for example, that shown in the prior U. S. Patent No. 2,071,677, and may comprise a manually operable hand wheel and a rack and gear mechanism for moving the work supporting table longitudinally. This mechanism is not considered to be a part of the present invention and consequently has not been illustrated or described in detail. For further details of the manual traversing mechanism, reference maybe had to the U. S. Patent above referred to.

A table actuated mechanism is provided for initiating a shifting movementof the reversing valve 25, comprising a reversing lever which is supported on a rock shaft 88. 'The rock shaft 88 is joumalled in a bearing 81. formed in the apron 88. A short downwardly extending lever 88 is fixedly mounted on th inner end of the rock shaft 88 and is provided with a stud 88 which engages or rides in a vertically extending groove 88 formed in the valve stem 28. The reversing lever 85 is provided with a rearwardly extending stud 8| which is arranged in the path of a pair of adjustably mounted table dogs 82 and 83. The table dogs 82 and 93 are adjustably supported by a T-slot 94 formed in the front face of the work supporting table I I.

As illustrated in Fig. 1, fluid under pressure entering the valve chamber or passage 34 may pass through either a port 85 or a port 91 into either a. valve chamber I88 of a valve chamber I 8| respectively. The valve chambers I88 and IM areformed between the valve pistons 29, 38, 32 and 33, respectively. Fluid under pressure passes from the chambers I 88 and IN, through ports I82 and I83, into reservoirs 98 and 89, respectively, formed within the end portions of the valve 25.

The effective areas of the pistons 28 and 33 are considerably less than the effective areas of the valve pistons 38 and 32, respectively. By providing the differential in pressure areas between these pistons, the valve chambers I88 and III serve to function as a pilot valve and cause a reversal of the reversing valve 25 under the influence of fluid pressure whenever the valve is moved to a position slightly by the center position; that is, so that either the port 85 or the the left. as viewed in Fig. 1.

A rotary type valve I85 is provided for controlling the exhaust of fluid from the reservoirs 88 and 88, respectively. The valve I85 comprises a pair of disk-shaped valve members I88 and I8'I which are adjustably fastened together by means of a clamping screw I88. The clamping screw I88 passes through an arcuate-shaped elongated slot I 89 formed in the valve member I88 and is screw threaded into the valve member I81. A circular-shaped strap II8 surounds the periphery of the disk-shaped valve member I88 and is fixedly fastened to a supporting plate II I. A clamping screw 2 (Fig. 1) is arranged to clamp the strap in adjusted position relative to the disk-shaped valve member I88.

It will be readily apparent from the foregoing disclosure that the valve members I 88 and I81 are adjustable relative to each other and are angularly adjustable by loosening the supportsage I33.

fastened to the left-hand end of the valve piston 29. A pair of opposed spaced stop screws H1 and H8 are suported by a bracket H9 which is fixedly mounted in position onthe valve member I01. The screws H1 and H8 are arranged in the path of a downwardly extending projection I I4a of the valve actuating lever I I4 and serve to limit the oscillatory stroke of the lever H4 as desired.

Only a slight motion of the valve rotor H3 is required; consequently it is desirable to provide a frictional connection between the valve actuating lever H4 and the link H5 so that the reversing valve 25 is free to move through its entire extent, This friction device may comprise a stud portion I20 formed integral with the link H5 which passes through an elongated arcuateshaped slot I2I formed in the upper end of the lever H4. A pair of friction washers I22 and The operation of the improved table traversing mechanism will be readily apparent from the foregoing disclosure. Assuming the tablev II to be traveling toward the left, as indicated by the arrow in Fig. 1, this movement continues until the table dog 93 engages the stud M on the redirection. This movement of the reversing lever shifts the valve piston 28 toward the right (Fig.

versing lever 85 to rock it in a counterclockwise 1) so thatthe valve piston 3| gradually closes the port 48 to cut of! the exhaust of fluid from the cylinder chamber 42. As soon as the valve piston, 30 moves .sufliciently toward the right under the influence of the reversinglever 85 to uncover the port 96, fluid under pressure is admitted to the valve chamber I00- During thisinitial movement of the reversing valve 25, the rotary valve I05 is actuated, that is, the lever H4 is shifted in a .I23 are supported on the stud I20 and are arranged on opposite sides of the lever H4 (Fig. 3).

A compression spring I24 surrounds the stud I20 and is interposed between a nut I25 supported on the threaded stud I20 and the friction washer I22. By adjusting the nut I25, the compression of the spring I24 may be varied as desired to provide the desired frictional connection between the link H5 and the lever H4.

A pipe I connects the reservoir 99 with a passage or port I3I formed inthe valve'member I0'l. Similarly, a pipe I32 connects the valve reservoir 99 with a passage or port I33 formed in the valve member I06. The valve rotor H3 is provided with a central chamber I34 which is connected by a pipe I35 with the reservoir 2|.

- that any fluid leaking by the pistons clockwise direction (Figs. 1 and 5)'so that the passage I31, is aligned with the passage or port I33. At the same time, the passage or port I36 is thrown out of alignment with the port or passage I3I into the position shown in Fig. 6. With the part asillustrated in Fig. 6, fluid within the reservoir 99 is free to exhaust I32, through the portor passage I33, and the port" or passage I31 and to pass through the central passage I34 in the rotary valve part H3 and out through the pipe I35 into the reservoir 2I.

When the valve is in the position illustrated in Fig. '6, the port or passage I3I is closed so 29 or 30 is confined within the reservoir 98 and cannot pass through the exhaust pipe to the reservoir 2I. As soon as the port 96 is uncovered by movement of the valve piston 30 toward the "right,

A pair of radially extending passages or ports I36 and I3! are provided in the valve rotor H3; These ports or passages I36 and I3! are arranged alternately to align with the ports or passages IM and I33, respectively, formed in the stationary part of the valve I05. 1

By adjusting the stop screws H1 and H8, the oscillatory stroke of the lever 4 may be varied as desired. The stop screw H'I serves to limit the stroke of the lever H4 in a clockwise direction (Fig. 6) so that in its end position, the port or passage I31 is aligned with the port or pas- Similarly, the stop screw I I8- is ad- Justed to limit the swinging movement of the fluid under pressure entering the valve chamber )0, due to differential piston areas of the pistons 29 and 30, serves to shift the valve stem 28 toward the right into its extreme right-hand end position so that fluid under pressure from the pump 23 passing through the pipe 24 enters the valve chamber 41 and passes through the port 46, the passage 45, the pipe 44,- into the cylinder chamber 42 to start the table II moving toward the right (Fig. l).

lever H4-in a counterclockwise direction (Fig. 5)

. pressure may be utilized to shift the valve 25 into its reverse position. Similarly, when the parts of the valve I05 are reversed at theother end of the table stroke, the valve I05 prevents leakage of fluid by the valve pistons 32 and 33 from exhausting into the reservoir so that the full effect of the fluid under pressure within the system may be utilized to shift the reversing valve 25 into its reverse position.

During the latter part of the shifting movement of the reverse valve25, the rotary valve I05 remains stationary and due to the friction device above described, the stud I20 slides within the elongated slot I2I. It ,will be readily apparent that the rotary member H3 of the valve I05 only moves through a slight angular stroke during the initial shifting movement of the valve piston 28 in either direction.

The operation of the reversing mechanism is substantially identical atthe other end of the table stroke; the valve I05 is shifted during the initial movement of the reversing valve 25 so that fluid is free to exhaust from the reservoir 98 while fluid is confined within the reservoir 99.

If it is desired to stop the reciprocatory movement of the table II, the control lever 65 may be shifted in a clockwise direction into position 65a. This movement serves to shift the valve piston 51 to close the V-port 52,-thus cutting off exhaust of fluid from the table cylinder I2. When the valve 5I is in a stopped position, the pipe 80 is directly connected with the pipe 8.I through a valve chamber 82 which is then in position 82a shown in broken lines in Fig. 1, so that fluid may readily by-pass between the cylinder chamber M and the cylinder chamber 42 to through the pipe facilitate a manual traversing or adjusting movement of the table II.

It will thus be seen that there has been provided by this invention apparatus in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved. As many possible embodiments may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawing is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. In a grinding machine having a longitudinally reciprocable table, a piston and cylinder to reciprocate said table, means including a piston type reversing valve to convey fluid under pressure to either end of said cylinder, means in-' cluding a reversing lever and adjustable dogs to actuate said reversing valve, pressure chambers in the ends of said reversing valve which serve to shift said valve, enclosed reservoirs in each end of said reversing valve to re, vive'fluid from said end chambers, and a' -con'tr falve actuated by and intimed relationwith 'said reversing valve to prevent exhaust of fluid from one of said reservoirs while allowing free exhaust of fluid from the other reservoir to facilitate shifting of the reversing valve into a reverse position.

2. In a grinding machine having a longitudi- I nally reciprocable table, a piston and cylinder to reciprocate said table, means including a piston type reversing valve to convey fluid under pressure to either end of said cylinder,- means including a reversing lever and adjustable dogs to actuate said reversin valve, pressure chambersin the ends of said reversing valve which serve to shift said valve, enclosed reservoirs in each end of said reversing valve to receive fluid from said end chambers, and a rotary type control valve actuated by and in timed relation with said reversing valve to prevent exhaust of fluid from one of said reservoirs while allowing free exhaust of fluid from the other reservoir to facilitate shifting of the reversing valve into a reverse position.

3. In a grinding machine having a longitudinally reciprocable table, a piston and cylinder to reciprocate said table, means including a piston type reversin valve'to convey-fluid under pressure to either end of said cylinder, means including a reversing lever and adjustable dogs to actuate said reversing valve, pressure chambers in the ends of said reversing valve which serve to shift said valve, enclosed reservoirs in each end of said reversing valve to receive fluid from said end chambers, a control valve actuated by and in timed relation with said reversing valve, and operative connections between said rotary valve and said reservoirs to prevent exhaust of fluid from one of said reservoirs while allowing free exhaust of fluid from the other reservoir to facilitate shifting of the reverse valve into a reverse position.

4. In a grinding machine having a longitudinally reciprocable table, a piston and cylinder to reciprocate said vtable, means including a piston type reversing valve to convey fluid under pressure to either end of said cylinder, means including a reversing lever and adjustable dogs to actuate said reversing valve, pressure chambers in the ends of said reversing valvew'hich serve to shift said valve, enclosed reservoirs in each end of said reversin valve to receive fluid from said endchambers, a rotary type control valve actuated by and in timed relation with said reversing valve, and operative connetcions between said rotary valve and said reservoirs to prevent exhaust of fluid from one of said reservoirs while allowing free exhaust of fluid from the other reservoir to facilitate shifting of the reverse valve into a reverse position.

5. Ina grinding machine having a longitudinally reciprocable work table, a piston and cylinder to reciprocate said table, means including a piston type reversing valve to convey fluid under pressure to either end of said cylinder, means including a reversing lever and adjustable dogs to actuate said valve, pressure chambers in the ends of said reversing valve formed between spaced valve pistons therein, the adjacent pistons of each chamber having differential effective areas to facilitate shifting of the reversing valve when fluid under pressure is admitted to the end chamber, enclosed reservoirs in each end of said reversing valve to receive fluid from said end chambers, and a control valve actuated by and in timed relation with said reversing 'valve to prevent exhaust of fluid from one of said reservoirs while allowing free exhaust of fluid from the other reservoir to facilitate shifting of the reversing valve into a reverse position.

6. In a grinding machine having a longitudinally reciprocable work table, a piston and cylinder to reciprocate said table, means including a piston type reversing valveto convey fluid under pressure to either end of said cylinder, means including a reversing lever and adjustable dogs to actuate said valve, pressure chambers in the ends of said reversing valve formed between spaced valve pistons therein, the adjacent pistons of each chamber having differential effective areas to facilitate shifting of the reversing valve when fluid under pressure is admitted to the end chamber, enclosed reservoirs in each end of said reversing valve to receive fluid from said end chambers, ports connecting said end chambers with said reservoirs, respectively, and a control valve actuated by and in timed relation with said reversing valve to prevent exhaust of fluid from one of said reservoirs while allowing free exhaust of fluid from the other reservoir to facilitate shift-' ing of the reversing valve into a reverse position.

'7. In a grinding machine having a longitudinally reciprocable work table, a piston and cylinder to reciprocate said table, means including a piston type reversing valve to convey fluid under pressure to either end of said cylinder, means including a reversing lever and adjustable dogs to actuate said valve, pressure chambers in the ends of said reversing valve formed between spaced valve pistons therein, the adjacent pistons of each chamber having differential effective areas to facilitate shifting of the reversing valve when fluid under pressure is admitted to the end chamber, enclosed reservoirs in each end of said reversing valve to receive fluid from said end chambers, and a control valve operatively connected to control the exhaust of fluid from said reservoirs which is actuated by and in timed relation with said reversing valve to prevent ex including a reversing lever and adjustable dogs to actuate said valve, pressure chambers in the ends of said reversing valve formed between spaced valve pistons therein, the adjacent pistons ated by and in timed relation with said reversing valve to prevent exhaust of fluid from one of said reservoirs while allowing free exhaust of fluid from the other reservoir to facilitate shifting of the reversing valve into a reverse position.

9. In a grinding machine having a longitudinally reciprocable work table, a piston and cylinder to reciprocate said table, means including a piston type reversing valve to convey fluid under pressure to either end of said cylinder, means including a reversing lever and adjustable dogs to actuate said valve, pressure chambers in' the ends of said reversing valve formed between spaced valve pistons therein, the adjacent pistons of each chamber having difierential effective areas to facilitate shifting of the reversing valve when fluid under pressure is admitted to the end chamber, enclosed reservoirs in each end of said reversing valve to receive fluid from said end chambers, a control valve operatively connected to control the exhaust of fluid from said reservoir which is actuated by and in timed rela- 35 tion with said reversing valve, and adjustable stops to limit the movement of said control valve in either .directiomsaid control valve serving to prevent exhaust of fluid from one of said reservoirs while allowing free exhaust of fluid from the other reservoir to facilitate a positive shifting of the reversing valve into a reverse position.

' 10. -In a grinding machine having a longitudinally reciprocable work table, a piston and, cylinder to reciprocate said table, means including a to control the exhaust of fluid from said reservoirs, adjustable stops to limit the movement of said control valve in either direction, and frictional connections between said reversing valve and said control valve whereby the control valve is actuated during the initial movement of said reversing valve in either direction to prevent exhaust of fluid from one of said reservoirs while allowing free exhaust of fluid from the other reservoir to facilitate a positive shifting of the reversing valve into a reverse position.

DONALD H. HOLMES. 

